G.A. Tuskan(1), S.P. DiFazio(1), P. Lammers(2), F. Martin(3), G. Newcombe(4), G.K. Podila(5)
(1) Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830
(2)Department of Chemistry and Biochemistry, New Mexico State University, P.O. Box 3001, Dept 3MLS, Las Cruces, NM 88003-8001
(3) College of Natural Resources, University of Idaho, Moscow, Idaho 83844-1133
(4) UMR INRA/UHP 1136, Interactions Arbres/Micro-Organismes, INRA-Nancy, 54280 Champenoux, France
(5) Department of Biological Sciences, University of Alabama, Huntsville

Within the framework of the Microbial Genome Program of the US Department of Energy (DOE), we have proposed a bold sequencing initiative that would result in an unprecedented view of the complex endophytic and symbiotic communities associated with the model tree Populus. The perennial nature of Populus facilitates the evolution of consortia of microorganisms that shape responses to global climate change or stresses from environmental contaminants. Characterization of the Populus mesocosm would allow in-depth exploration of the coordinated community response to these stressors, thus adding a needed dimension to climate change research and providing another step in the quest for mechanistic modeling of ecosystem responses. To this end, we have proposed genome sequencing for several known Populus associates: Glomus intraradices, a vesicular-arbuscular endomycorrhiza, Laccaria bicolor, an ectomycorrhiza that colonizes a broad range of economically important trees, and Melampsora laricii-populina, a leaf rust fungus that causes widespread economic damage. In addition, we have proposed shotgun sequencing of DNA representing leaf, stem, and root-associated fungal and microbial communities, all of which are largely unexplored sources of genetic variation that shape responses of the host tree to the environment. In October 2003, Glomus intraradices and Laccaria bicolor have been selected for complete genome sequencing in 2004. This project will provide unprecedented insights into the molecular bases of symbiosis, pathogenicity, and adaptation, and will be a major step toward moving genomic research into the realm of ecosystem science.